Sun dial



De'c, 1, 1964 P. JEAN-BAPTISTE FLlNols 3,158,937

' SUN DIAL Filed March 2. 1962 `2` Sheets-Sheet 1 Dec. l, 1964 FiledMarch 2, 1962 P. L. JEAN-BAPTISTE FLINOIS SUN DIAL.

ZSheets-Sheet 2 which:

United States Patent O 3,358,937 SUN DIAL Pierre Laurent .lean-Baptisteillinois, 3S line Sibuet,

Paris, France Filed Mm. 2, i962, Ser. No. 177,025 vClaims priority,appiicationFrance, Mar. i3, 1961,

ia claims. ici ssa-sa) In all sun dials at present known kuse is made ofthe p shadow of a style on a table, which is a flat or vcurved i of.revolution one of the ends of which is open, permit only veryy diiicultreading of the shadows.

The present invention, which relates toma new sun dial free from theabove-mentioned disadvantages, consists of a curved, open, suitablyselected surface on which the hour lines are traced.

The curved surface is geometrically delined as a concave ruled surfacewhich means that the surface is pro- Y duced by a straight linegenera'trix moved in a position parallel with a stationary straight linealong a curve which 'has no breaks and contains no change inthedirection of its curvature. Thus, this term'also includes cylindricalsurfaces in which case, as is well known, the crosssection need -not'bea circular arc. Therefore, in the followingv spemication and in theclaims the term concave cylindrical surface is intended to deiinebroadly a concave ruled surface as stated above. v

Two parallel generatrices which bound the said concave cylindricalsurface act as style.

The invention permits the serial production of inexpensive apparatuseswhich everywhere show V,the legal time to Within one minute. n

Many diiierent surfaces may be used. There are numerous mechanicalconstructions permitting their positioning in accordance with the placewhere nthey are used.

The present invention likewise relates to other arrangements which willbe explained below in the description of the dials illustrated in the`accompanying Y drawings, 1n

FIGURE l is a'view in elevation offa rstsun dial according to thepresent invention and of the various means of support and-regulation ofthe said dial,

FIGURE 2 is a view of a detail of the said dial, FIGURES is a partialview of the sun dial illustrated in FIGURE 1, viewed in' the directionot the` arrow f,

FIGURE 4 isa section along the line in FlG- URE 3, and l FIGURE 5 isaView of a second sun dial according to the present invention and of thevarious means of support and regulation of the said dial.

The sundial illustrated in Mouans 1 a; 4 is here constituted by apartialV cylinder of revolution l. The

i aises? Patented Dec. l, 19614 IC@ Y poles of the earth, theshadowscast by the generatrices la or lb on the vdial-formed by thecylinder 1 give the true local time. The cylinder lpbears a number ofhour line ld, each of these lines corresponding to two times, differingfrom one another by live hours, depending on whether the shadow is castby the generatrix laY or the generatrix lb. y

The cylinder l is solid with a stirrup 2 adapted to pivot around animaginary line formed by the axes of two buttons 4 and 5 carried by astirrup 3. This line is parallel to the generatrices of the cylinder l.

The stirrup 3 forms one side of a deformable triange channel member l@carries a latitude graduation scale.

The channel member il? rests on a disc l2 which is fixed by screws ll3to a base I4, having three feet formed by adjusting screws I5.

A screw i7 passing through the disc l2 serves as axis of rotation forthe channel member 10 and passes through` A pointer. I9 pivoting aroundthe axis of the button 4 'v is adapted to move in front of the plate i8,so that when the button Li is tightened the pointer 19 forms a rigidwhole with the stirrup 2 and the cylinder l.

Finally,` the two stirrups 2 and 3 can be clamped together by a pin E@or by the button 5.

For the purpose of installing this sun dial the pro- V cedure isadvantageouslyas follows:

In order to set the channel lll horizontally, the positions of thescrews l5 are adjusted in a manner known per se bymeans of a waterlevel.

ln order to adjust the apparatus to latitude, the button '16 isloosened, the cursor 9 is so adjusted as to have its end on the latitudescale graduation provided on the bot- I must be brought parallel to theearths axis.

tom of the channel member lll, which corresponds to the latitude of theplace where the sun dial is installed, and the button 16 is tightenedagain.

In order to adjust the apparatus, the axis llc of cylinder For thispurpose it is now suliicient to bring the channel Vmember l@ into thelocal meridian plane. The cylinder l is clamped to the assembly 3, 9,it), S, by means Vof the pin 2li. The button 4 is loosened andconsequently the pointer i9 released and the latter is set to thegraduation of the longitude scale 18h corresponding to the longitude ofthe apparatus in relation to the Greenwich meridian.

The pointer 19 is finally clamped again by tightening the screw button 4to the stirrup 2 and the cylinder l.

The pin Ztl is removed and the button 5 loosened. The

assembly l, 2, 19, can then be turned in relation to generatrices laandy lib, which coincide with the edges of said partialvcylinder l andare spaced from eachother a distance subtending an angle or arc a=l ofsaid cylmeridian plane of the place where the sun dial is ,in-

7 stalled, passing through the axisof the said cylinder, and

when Vthese generatrices are parallel to the axisk of the ytonS.y e

The direction of` the apparatus is then'adjusted by loosening the buttonI6 and theV entire apparatus is ad-V the assembly 3, i8. The assembly l,Z, i9 is vturned `so that the pointer i9 is set-to the` graduation ofthe time curve lita corresponding to the date on which the instrument isinstalled. The assembly l, 2, l? is again clamped to the assembly f3,i8, by tightening the but- 'l justed so that the shadow of thegeneratrix la or lb v on the cylinder I indicates the legal time, andthe but- Y ton 1d is finally tightened again. The Aapparatus is then inposition.

Every ten days Vthe apparatus must be re-adjusted. For l this purposethe lbutton 5 is released and the pointer The Y said 1 vorder to bringthe channel member l@ into t il@ is set to the graduation or the timecurve ida corresv onding to the date of the correction and then thebutton 5 is tightened again.

The apparatus thus shows the legal time throughout the year to within lminute.

Diurnal shadow lines or lines of equal dates can easily be traced on thedial of this instrument. The latter then becomes self-regulating becauseit can be installed Jithout the time being known.

ln the apparatus illustrated in FlGURE 5, the stirrup 2 is mounteddirectly on the raised end 9b of the cursor 97. The button 5 and alsothe plate i8 and its pointer i9 are eliminated. The pin 2@ is thenplaced on one of the sides 2o of the stirrup 2 and on a part 2l, solidwith a part Z2. rticulated by means of the hinge d on the bar 8.

The remainder of the apparatus is similar to that illustrated inFlGUltlS l and 2.

ln order to install this last-mentioned sun dial, the procedure may beas follows:

ln order to set the channel member l@ horizontally to regulate theapparatus for latitude, the procedure is as before.

ln order to orient the apparatus, that 's to say in meridian planepassing through the place where the sun dial is situated, the procedureis as vfollows: the pin 2u remains engaged, the button it? is loosened,and the instrument is brought into a position such that the diilercncebetween the time indicated on the cylinder it by the shadow cast by thegeneratrices and lo and the legal time is equal to a Value given by atable in dependence on the date on which the instrument is beinginstalled and on the longitude of the place in relation to the Greenwichmeridian. The button iti is then tightened. rEhe channel member itl isthen in the meridian plane of the place.

ln order to adjust the position of the cylinder, the pin is removed andthe cylinder l turned until the aforesaid difference is equal to zero,and the assembly is clamped by means of the button 4.

The apparatus is then adjusted in place.

Every eight days the button d is loosened and the cylinder l' and itsstirrup 2 turned until it indicates the legal time, and the button i istightened again.

lt should be observed that the accuracy of the instruments described istwice as great as that of cylindrical dial instruments having axialstyles, because in the instruments according to the present inventionthe generatrices la and lib are in the dial surface, whereas in thecylindrical instruments having an axial style the style is in thecentre.

Tie present invention is not limited to the examples described. Thus,tor example, the dial is not necessarily constituted by a split cylinderof revolution. This dial may in fact be constituted by a skew surfacebounded by two parallel generatrices. ln particular, where use is madeof a hyperboloid of one sheet, the dial carries crossing hour lines.

l claim:

l. A sundial apparatus, comprising, in combination, opaque dial platemeans having a concave cylindrical indicating surface adapted to beexposed to incident sunlight and to unobstructed view, and denedgeometrically as a portion of a cylindrical surface extending betweentwo parallel edges each coinciding with a generatrix of said indicatingsurface and being located in generally opposed direction across saidindicating surface, said indicating surface being provided with aplurality of index lines respectively associated with different hours ofthe day; and means for orienting said dial plate means at leastdepending upon latitude and longitude of the location of the apparatus,so that the time indication is cliected on said indicating surface ofthe dial plate means in relation to said lines by the edge of the shadowl of a portion of said opaque dial plate means, said edge or" the shadowbeing a projection by sunlight of one of said edges of said dial platemeans.

2. A sundial apparatus, comprising, in combination, opaque dial platemeans having a concave indicating surface adapted to be exposed toincident sunlight and to unobstructed view, and defined geometrically asa portion of a cylindrical surface extending between two parallel edgeseach coinciding with a generatrix of said cylindrical surface and beingspaced from the other generatrix a predetermined distance substantiallydiametcally across said cylindrical surface, said indicating surfacebeing provided with a plurality of index lines respectively associatedwith different hours of the day; and means for orienting said dial platemeans at least depending upon latitude and lonvitude of the location ofthe apparatus, so that the time indication is eilected on saidindicating surface of the dial plate means in relation to said indexlines by the edge of the shadow of a portion of said opaque dial platemeans, said edge of the shadow being a projection by sunlight of one ofsaid edges of said dial plate means.

3. A sundial apparatus, comprising, in combination, opaque dial platemeans having a concave indicating surface adapted to be exposed toincident sunlight and to unobstructed view, and defined geometrically asa portion of a cylindrical surface extending between two parallel edgeseach coinciding with a generatrix of said cylindrical surface and beingspaced from the other generatrix a predetermined distance subtending aarc of said cylindrical surface, said indicating surface being providedwith a plurality of index lines respectively associated with differenthours of the day; and means for orienting said dial plate means at leastdepending upon latitude and longitude of the location of the apparatus,so that the time indication is effected on said indicating surface ofthe dial plate means in relation to said index lines by the edge of theshadow of a portion of said opaque dial plate means, said edge of theshadow being a projection by sunlight of one of said edges of said dialplate means.

4. A sundial apparatus as claimed in claim 1, wherein said opaque dialplate means include support means turnable about an axis parallel withthe geometrical axis of said cylindrical surface, and wherein said meansfor orienting said dial plate means include pivot means turnablysupporting said dial plate support means for turning movement about saidaxis and clamping means for setting said dial plate means in a desiredoriented position.

5. A sundial apparatus as claimed in claim 3, wherein said opaque dialplate means include support means turnable about an axis parallel withthe geometrical axis of said ruled surface, and wherein said means fororienting said dial plate means include pivot means turnably supportingsaid dial plate support means for turning movement about said axis.

6. A sundial apparatus as claimed in claim 4, wherein said means fororien'ting said dial plate means include a triangular supporting framecomposed or" a plurality of frame members, one frame member carryingsaid pivot means and being adjustable to a desired inclination relativeto a second one of said frame members.

7. A sundial apparatus as claimed in claim 5, wherein said means fororienting said dial plate means include a triangular supporting framecomposed of a plurality of frame members, one frame member carryinggsaidpivot means and being adjustable to a desired inclination relative Ito asecond one of said frame members.

8. A sundial apparatus as claimed in claim 6, wherein said triangularframe comprises a plurality of hingedly connected frame members, one ofsaid frame members being composed of at least two portions, one of whichis longitudinally adjustable relative to the other portion for Varyingthe length of that particular frame member, said other portion carryinga latitude scale and said adjustable portion being movable relative tosaid scale so that it can be set to a position relative to said scalewhich determines a desired inclination of said axis of said dial platemeans.

9. A sundial apparatus as claimed in claim 8, wherein said one framemember carrying said pivot means includes a plate member carrying alongitude scale, and wherein said dial plate support means include anindex member movable relative to said longitude scale for indicating thesetting of said dial plate means corresponding to a particular longitudewhen said dial plate means are correspondingly turned about its axis.

10. A sundial apparatus as claimed in claim 9, including an indexed timecorrection curve arranged on said plate member for cooperation with saidindex member and permitting adjustment of said dial plate means inconsideration of the difference between apparent time and clock time.

References Cited in the le of this patent UNITED STATES PATENTS 170,423Wheeler Nov. 23, 1875 825,319 Hewitt July 10, 1906 10 3,031,763 JewettMay 1, 1962 FOREIGN PATENTS 915,671 France July 29, 1946

2. A SUNDIAL APPARATUS, COMPRISING, IN COMBINATION, OPAQUE DIAL PLATEMEANS HAVING A CONCAVE INDICATING SURFACE ADAPTED TO BE EXPOSED TOINCIDENT SUNLIGHT AND TO UNOBSTRUCTED VIEW, AND DEFINED GEOMETRICALLY ASA PORTION OF A CYLINDRICAL SURFACE EXTENDING BETWEEN TWO PARALLEL EDGESEACH COINCIDING WITH A GENERATRIX OF SAID CYLINDRICAL SURFACE AND BEINGSPACED FROM THE OTHER GENERATRIX A PREDETERMINED DISTANCE SUBSTANTIALLYDIAMETCALLY ACROSS SAID CYLINDRICAL SURFACE, SAID INDICATING SURFACEBEING PROVIDED WITH A PLURALITY OF INDEX LINES RESPECTIVELY ASSOCIATEDWITH DIFFERENT HOURS OF THE DAY; AND MEANS FOR ORIENTING SAID DIAL PLATEMEANS AT LEAST DEPENDING UPON LATITUDE AND LONGITUDE OF THE LOCATION OFTHE APPARATUS, SO THAT THE TIME INDICATION IS EFFECTED ON SAIDINDICATING SURFACE OF THE DIAL PLATE MEANS IN RELATION TO SAID INDEXLINES BY THE EDGE OF THE SHADOW OF A PORTION OF SAID OPAQUE DIAL PLATEMEANS, SAID EDGE OF THE SHADOW BEING A PROJECTION BY SUNLIGHT OF ONE OFSAID EDGES OF SAID DIAL PLATE MEANS.